While the effect of vertical loading on equine performance and injury is well known; there has been a limited discussion of grip.
The surface must sufficiently support the hoof but avoid excessive slip. Too much grip however, can increase shearing forces through the limb which can lead to injury.
Measurements of the ability of a surface to support the hoof must take into account the loads applied by the horse and movement specific loading patterns. So, for a galloping horse the forces are applied to the ground quickly in the vertical direction and there should be horizontal slide, but this should not be excessive.
A sharply-turning horse will lean inwards, re-directing some of the force from it”s bodyweight to make the turn. If the turn is really sharp it may also need to rotate it”s body around a planted limb. The surface needs shear resistance to make sure the horse doesn”t fall over when it leans, but some shear is needed to allow the planted foot to turn on the ground and the limb joints to be aligned correctly so as not to cause injury.
“There are currently few test devices that can provide realistic information about the rotational grip characteristics of equestrian surfaces, so the RACES team decided to address this problem”.
This led to the development of a novel apparatus, the Glen Withy torque tester (GWTT), which was designed and built by Glen Crook (formerly UCLan Senior Technician) with the help of the RACES team and Dr John Mather (formerly MMU, Head of Department, Engineering). Following calibration tests a UCLan internship was created to carry out a study to test the device, which included comparing it to the Orono Biomechanical Surface Tester (OBST) and a traction device that had previously been used to test arena surfaces.
We can measure more factors than ever…
The GWTT is considered to enhance the measurement capabilities that RACES have currently. When compared to the OBST the relationship between measurements was complicated and this was largely thought to be related to the speed of loading, as the OBST produces a dynamic load, whereas the GWTT produces more of a quasi-static load. RACES intend to continue to investigate the strain rate and non-linear load response of these arena surfaces. This data should be closely tied to the biomechanics of the horse and should include information on the maintenance condition and composition of the surfaces.